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BARIATRIC ANAESTHESIA (Anesthesia in Obese Patient )

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Presentation on theme: "BARIATRIC ANAESTHESIA (Anesthesia in Obese Patient )"— Presentation transcript:


2 BARIATRIC ANAESTHESIA (Anesthesia in Obese Patient )


4 Two Worst enemy of Anesthetist OBESITYCOPD

5 Obesity: Definition A condition in which excess body fat may put a person at health risk. (laymen) A chronic metabolic disorder that is primarily induced and sustained by an over consumption or underutilization of caloric substrate (Medical) The American Heart Association (AHA) defines obesity as body weight 30 percent greater than the ideal body weight (Precise)

6 Equations Ideal body weight in Kg (IBW) (Broca’s Index) –Height in centimeters  100 for men –Height in centimeters  105 for women –----------------------------------------------------- Body mass index (BMI) –weight in Kg / height (m) 2


8 Definitions Obese 20% > IBW BMI > 28 – 35 Morbidly Obese 2 x IBW BMI > 35

9 Obesity Classification Overweight - BMI > 25 kg/m2 Obesity - BMI > 30 kg/m2 Morbid obesity – BMI> 40 kg/m2 or 35 with coexisting co morbidities Super obese patient -BMI >50 kg/m2


11 My own BMI My weight is 80 kg My height is 5’8” (170 cm or 1.7 meter) So my BMI 82 / (1.7) 2 is 27.68 So I am Overweight but not obese


13 Incidence of Obesity in INDIA 23 % are obese 5% are morbidly obese –Mortality is 3.9 times that in non-obese


15 Causes of Obesity Complex and multifactorial –Genetic predisposition –Socialization –Age –Sex –Race –Economic status –Psychological –Cultural –Emotional –Environmental factors –Cessation of smoking

16 Diseases Linked to Obesity Diabetes Coronary Heart Disease High Blood Pressure ( Hypertension is about 6 times more frequent in obese subjects than in lean men and women ) Stroke Arthritis Gastroesophageal reflux Cancer High cholesterol Endocrine disease A 10-kg higher body weight is associated with a 3.0-mm Hg higher systolic and a 2.3-mm Hg higher diastolic blood pressure. These increases translate into an estimated 12% increased risk for CHD and 24% increased risk for stroke

17 Diseases Linked to Obesity Hypertrophic Cardiomyopathy Infertility Depression Obstructive sleep apnea Gallstones Fatty liver Stress incontinence Venous ulcers end-stage kidney failure Sudden death

18 Physical Complications of Obesity Heart disease Type II diabetes mellitus Hypertension Stroke Cancer (endometrial, breast, prostrate, colon) Gallbladder disease Sleep apnea Osteoarthritis Reduced fertility increased risk of morbidity and mortality as well as reduced life expectancy

19 Psychological Complications of Obesity Emotional distress Discrimination Social stigmatization anxiety, fear, hostility and insecurity

20 Diabetes Mellitus Type 2 prevalence is 2.9 times higher in the obese than in non-obese for those 20- 75 years of age. Morbidity due to Cardiovascular diseases has been reported to be almost 90 % in those with severe obesity.

21 Cardiovascular Pathophysiology in Obesity Excess body mass –  metabolic demand   CO For every 13.5 kg of fat gained: –25 miles of neovascularization occurs –Increased CO of 0.1 L/min for each kg of fat. –  workload LVH  pulmonary blood flow and HPV –Pulmonary HTN  cor pulmonale  right heart failure

22 Cardiovascular Pathophysiology in Obesity Stroke volume index and stroke work index are the same as non-obese SV and SW must  –Proportion to body weight  SV and SW –LVH dilatation

23 Cardiovascular Pathophysiology  risk of arrhythmias –Hypertrophy –Hypoxemia –Fatty infiltration of cardiac conduction system –  catecholamines –Sleep apnea –dyslipidemia –glucose intolerance


25 Cardiac Evaluation: Assess For Prior MI HTN Angina PVD

26 ECG Changes That May Occur in Obese Individuals ECG Changes That May Occur in Obese Individuals Heart rate PR interval QRS interval or QRS voltage QT c interval QT dispersion SAECG (late potentials) ST-T abnormalities ST depression Left-axis deviation Flattening of the T wave (inferolateral leads) Left atrial abnormalities False-positive criteria for inferior myocardial infarction

27 Cardiac Evaluation: ECG Determination of –resting rate –Rhythm –Ventricular hypertrophy or strain

28 Cardiac Evaluation: ECG Investigate ischemic changes or evidence of coronary artery disease Low voltage ECG –Excess overlying tissue Underestimate LVH

29 Cardiac Evaluation: ECG Axis deviation and atrial tachyarrhythmias Sudden cardiac death is more prevalent with –LVH –Ventricular ectopy

30 Cardiac Evaluation Indications of LV dysfunction –Limitations in exercise tolerance –History of orthopnea –Paroxysmal nocturnal dyspnea

31 Vascular Access Challenging at best –Excessive fat obscures blood vessels Central line placement –Vessels impeded by distortions of the underlying anatomy by adipose.

32 Volume Replacement Adult total body water percentage is 60% to 65%. Severely obese total body water is 40%. Estimated blood volume in obese patient is 45 to 55 mL/kg actual body weight –70 mL/kg for the non-obese

33 Volume Replacement Avoid rapid rehydration –Lessen cardiopulmonary compromise. Administer Hetastarch at recommended volumes per kilogram of IBW –20 mL/kg Albumin 5% and 25% used as indicated –Support circulatory volume and oncotic pressure. Replace blood loss with crystalloid –3:1 ratio

34 Respiratory Pathophysiology There is a clear association between dyspnea and obesity. Obesity increases the work of breathing because of the reductions in both chest wall compliance and respiratory muscle strength Excess metabolically active adipose +  workload on supportive respiratory muscle –  CO 2 production Hypercarbia –  O 2 consumption Hypoxia

35 Respiratory Pathophysiology Restrictive lung disease –Decreased chest wall compliance –Diaphragm forced cephalad –Decreased lung volumes –Accentuated by supine and Trendelenberg positions –FRC may fall below closing capacity Alveolar collapse –Ventilation / perfusion mismatch

36 Changes in Pulmonary Volumes and Function Tests Tidal volume –Normal or decreased Inspiratory reserve volume –Decreased Expiratory reserve volume –Greatly decreased

37 Changes in Pulmonary Volumes and Function Tests FRC –Greatly decreased –Direct inverse relationship between BMI and FRC FEV 1 –Normal or slightly decreased

38 Respiratory Pathophysiology Relatively hypoxemic Occasionally hypercapnic –Obesity-hypoventilation (Pickwickian syndrome) Obesity usually extreme Hypercapnia Cyanotic / hypoxemia Polycythemia Pulmonary HTN Biventricular failure Somnolence Obstructive sleep apnea syndrome (OSAS)

39 OSAS Definition –10 seconds or more of total cessation of airflow despite respiratory efforts Clinically relevant –5 episodes per hour –30 episodes per night

40 OSAS Snoring Dry mouth and short arousal during sleep Partners report apnea pauses during sleep

41 OSAS More vulnerable to airway obstruction –Opioids –Sedatives More vulnerable in supine or Trendelenberg position


43 OSAS and Difficult Intubation 15% of obese patients are a difficult intubation Short thick neck Obesity and short thick neck –Related to OSAS and to each other Fat in lateral pharyngeal walls are difficult to exam awake

44 Detecting OSAS Nocturnal polysomnography

45 GI Pathophysiology  incidence –Gastroesophageal reflux –Hiatal hernia –  abdominal pressure Severe risk of aspiration

46 GI Pathophysiology After 8 hour fast –85 – 90% of morbidly obese patients have Gastric volumes > 25 ml Gastric pH < 2.5

47 Anesthetic Considerations: Preoperative  risk for aspiration pneumonitis if reflux history –Consider H 2 antagonist ( pre, intra and post ) –Metoclopramide, Ranitidine or Ondansetron Sleep apnea, asthma, smoking Avoid unnecessary respiratory depressants BHT (breath holding time) Assess for –Cardiopulmonary reserve –ECG & X-ray Chest, if necessary echocardiography –LFT & RFT –ABG –PFT’s

48 Obesity: Anesthetic Issues AirwayAirway proper positioning can be difficultproper positioning can be difficult may need extra support under backmay need extra support under back POSITION, POSITION, POSITIONPOSITION, POSITION, POSITION

49 Anesthetic Considerations: Preoperative BP with appropriate size cuff Plan / examine for venous / arterial access –Possible regional anesthesia

50 Class I = visualization of the soft palate, fauces, uvula, anterior and posterior pillars. Class II = visualization of the soft palate, fauces and uvula. Class III = visualization of the soft palate and the base of the uvula. Class IV = soft palate is not visible at all. MallampatClassification Mallampati Classification

51 Anesthetic Considerations: Preoperative If HTN – good control Atherosclerosis then ECG &/or Stress Echo Previous anesthesia exposure and any problem to ask

52 Anesthetic Considerations: Preoperative Airway Assessment Limited TM joint mobility Limited atlanto-occipital mobility Narrow upper airway Small space between mandible and sternal fat pads

53 Neck Circumference Normal neck circumference in cm is weight in kg / 2 Normal neck cir. at 7o kg is 35 cm If it increase by 13 % then difficult intubation is counted

54 Obesity: Anesthetic Issues Respiratory SystemRespiratory System high risk of oesophageal reflux (GERD)high risk of oesophageal reflux (GERD) high risk of aspirationhigh risk of aspiration rapid sequence intubation (RSI) indicatedrapid sequence intubation (RSI) indicated pre-oxygenationpre-oxygenation cricoid pressurecricoid pressure succinylcholinesuccinylcholine

55 Anesthetic Considerations: Induction Prepare for difficult intubation Prepare for difficult mask ventilation Induction may cause airway collapse –Leading to upper airway obstruction

56 Induction Airway Equipment Light Stylet Gum elastic bougie Oral airway LMA’s ETT with stylet

57 Anesthetic Considerations: Induction Consider awake intubation –Avoids airway collapse –Minimal to no sedation –LMA is good alternative for temporary mechanical ventilation in grossly and morbid obese patient Consider tracheotomy kit and surgeon standing by

58 Anesthetic Considerations: Intraoperative Awake fiberoptic intubation if difficult airway suspected Breath sounds distant –ETCO 2 more important Relatively high FIO 2 may be needed in: –Lithotomy –Trendelenberg –Prone

59 VENTILATION In morbidly obese patients, the best strategy for ventilation is to deliver TV according to IBW (8-10 ml/kg ) Apply 5 cm H2O PEEP in order to decrease the incidence of atelectasis. Minute ventilation and ETCO2 need to be monitored closely Usually use pressure control ventilation

60 Best Position for Intubation External auditory meatus and sternal notch at same level

61 Obesity: Pharmacology Overdosing of pre medication and anesthesia drugs in obese patient is very common doses should be calculated on predicted “lean body weight” Lean body weight = body weight - fat weight Avoid IM injection due to unpredictable absorption If possible, avoid narcotics and sedation in obese patient

62 Obesity: Pharmacology Propofol at TBW Thiopental at IBW Midazolam at IBW Scolene at TBW Vcuronium at IBW Atracurium at TBW Rocuronium at IBW Fentanyl & Sufentanyl at TBW Remifentanil at IBW

63 Anesthetic Considerations: Intraoperative Positioning –2 OR tables side by side If > 350 lbs (150 kg) –Prone position is poorly tolerated Lateral decubitus is keeps abdominal weight off chest

64 Anesthetic Considerations: Intraoperative Morbidly obese patient should never lie flat –Semi-Fowler’s position Upper body elevated 30 – 40  Semi-recumbent position –Best position during post-operative period

65 Reverse Trendelenburg Position RTP is best intraoperative position –Can ameliorate deleterious effects of supine position RTP is 30 degree head up position RTP –  pulmonary compliance –  FRC –Returned P(A-a)O 2 to baseline RTP may be a better solution than –Large TV and PEEP Reverse Trendelenburg Position

66 monitoring ECG Pulse Oxymeter Blood pressure Temperature Inspired oxygen concentration Capnography Arterial catheter to continuously measure BP and blood gases ( if medically indicated ) CVP catheter Urinary catheter Advance monitoring according to Surgery If indicated then BIS

67 A – Anesthesia personnel M – Machine D – Drug Cart I – Infusion V- Visitor

68 Anesthetic Considerations: Intraoperative Pulmonary compliance and FRC  –Worsened by GETA and high intraabdominal pressure Opening the abdomen or lifting the panniculus –  FRC –Improves oxygenation

69 Anesthetic Considerations: Intraoperative Regional anesthesia –Technically more difficult –Require 20 – 25% less LA for Spinal or Epidural anesthesia because of (Epidural fat and distended epidural veins) Combined epidural/general(GA) preferred to decrease GA requirement Epidural anesthesia may  postoperative respiratory complications

70 Goals for Maintenance of Anesthesia Strict maintenance of airway Adequate skeletal muscle relaxation Optimum oxygenation Maintenance of anesthesia with inhalation and intravenous agents Avoid residual effects of muscle relaxants Appropriate intraoperative and postoperative tidal volume Effective postoperative analgesia.

71 Anesthetic Considerations: Postoperative Respiratory failure risk increased by –Preoperative hypoxia –Thoracic or upper abdominal surgery Vertical incision Delayed extubation until –Complete reversal of muscle relaxation –Patient fully awake Follows commands

72 Anesthetic Considerations: Postoperative Supplemental O 2 after extubation –Transport from OR to Recovery room 45 degree head up position –Unload diaphragm –Improves oxygenation –Improves ventilation –CPAP and BiPAP should available

73 Anesthetic Considerations: Postoperative Increased mortality –6.6% vs. 2.7% in non-obese Absolute no sedation post op Increased risk –Wound infection –DVT –PE

74 Anesthetic Considerations: Postoperative PCA –Can provide good pain relief –Dose based on IBW NSAIDs, Local anesthetic infiltration Epidural route is preferred –Administration of smaller dose than IV route

75 Airway Management of the Obese Formulate an airway management plan Facial anatomy needs appropriate mask selection Increased mass of soft tissues and Macroglossia Weight of head Head Tilt & "Sniffing Position" may require building up towels or blankets under the back, scapulae, and shoulders, as well as the head and neck beware of "can’t ventilate, can’t intubate" situations! Mask ventilation may require two persons: one to use two-handed mask technique with triple airway maneuver, airway device, and CPAP; with another to bag the patient and monitor effectiveness appropriately sized oropharyngeal or nasopharyngeal airway "Bull Neck" – short, thick neck inhibits mobility and makes visualization of the larynx difficult during laryngoscopy. Have "rescue" alternative airway devices ready to hand: e.g., Laryngeal Mask Airway (LMA) or Intubating LMA (Fastrach™); Elastic Gum Bougie; Lighted Stylet; Esophageal Combi-Tube™; Fiber-optic Laryngoscope or Bronchoscope

76 Airway Management of the Obese The first intubation attempt should be by the most experienced intubator If the first best attempt determines difficult or impossible laryngoscopy or intubation, change to either Rescue Airway plan (if patient condition is critical), or early Fiberoptic Intubation before airway trauma worsens the situation Large breasts may get in the way of the laryngoscope handle (half- size handles are available). Response to induction agents is less predictable for intubation Confirmation of endotracheal intubation should be by three or more methods including either capnometry or capnography Obese patients will desaturate oxygen rapidly All obese patients with airway problems or impending intubation should have 100% oxygen In failed Intubation by all methods, in emergency Percutaneous cricothyrotomy or surgical tracheostomy

77 Case study of female obese patient posted for Umbilical Hernia Repair at Sangam Hospital 55 year old female Height 5’2” ( 1.55 meter ) Weight 114 kg BMI 47.5 ASA Physical Status II BP 142/82 mm hg & Resting pulse 82 / mn Spo2 at room air 93 % Mild asthma EF > 50 No other positive personal, past or family history ECG and X-ray chest were normal Lab investigations WNL Negative history of GERD, snoring and obstructive sleep apnea

78 On Examination Very obese patient Very short neck Mallampati class II airway Patient was needing two pillows in supine Two anesthetist were there Two IV line taken with 20 # veinflon

79 Preparation Pre oxygenation started with 5 liter through nasal prongs Multi parameter (NK) put including Spo2, ECG, Large BP cuff (NIBP), Temperature probe Patient put supine 30 degree RTP position with 2 pillows under head One nebulizer puff of bronchodilator given

80 Premedication Glycopyrolate 1 ml IV Rantac 2 ml IV Emeset 4 ml Lyceft 2 gm IV Fentanyl 100 mcg IV Midazolam 2 mg IV Voveran 3ml IV diluted Xylocard 5 ml IV

81 INDUCTION Propofol 1.5 mg / kg IV slowly with total 17 ml given Immediately put large size oro pharyngeal airway Cricoid pressure applied Spontaneous ventilation maintained and assisted prior to intubation

82 Intubation Cricoid pressure applied Scolene 150 mg given fast IV Laryngoscopy and Intubation with 7 # cuff ET with stylet were performed uneventfully Cuff pressure 7 ml applied with air Not much threatening changes were noted on multi Para monitor

83 Maintenance Patient put on max ventilator with TV 900 ml ( 8 ml/kg) and RR 16 / min Capnograpgy put between ET and Ventilator Atracurium 50 mg IV bolus Oxygen 3 lit and Nitrous Oxide 3 lit with Isoflurane 2 mark Continuously given Atracurium repeated 15 mg around every 30 minutes No adverse cardiac or respiratory events occurred Total 1500 ml RL given intra operative

84 At the end Nitrous Oxide and Isoflurane discontinued and Oxygen 100 % around 5 lit continued Neuromuscular blockade reversed with neostigmine 5 mg IV and Glycopyrrolate 1 mg IV Mechanical ventilation discontinued upon resumption of spontaneous ventilation

85 Recovery Patient opened eyes and responded to command approximately 5 minutes after reversal. No coughing or breath holding noted Spontaneous ventilation, with sustained head lift and oxygen saturation maintained > 95 % Extubation performed uneventfully Patient transferred to recovery ward in left lateral position with oxygen 3 lit via nasal route Total surgical time was 1 hour 25 minutes and total anesthesia time was 1 hour 40 minutes

86 Transfer Patient put 30 degree head up in recovery room Patient transferred from recovery to special room after 6 hours No major or life threatening changes in vitals noted in post op period Patient discharged after 8 days

87 Message The anesthetic management of the clinically severe obese patient requires meticulous preoperative, perioperative and postoperative care. Careful planning is essential before taking the patient in the operating room. To have excellent outcome, a multidisciplinary approach, including the primary care physician, anesthesiologist, surgeon, nursing staff and social worker is necessary.

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